US envoy Stephen Bosworth ended a three-day visit to North Korea on Thursday, reportedly saying he had "very useful" contacts aimed at bringing the communist state back to nuclear disarmament talks.
His trip was the first official contact between Washington and Pyongyang since US President Barack Obama took office in January. He had pledged direct diplomacy with America's adversaries.
"It's a very useful meeting," China's Xinhua news agency quoted Bosworth as saying at Pyongyang's Sunan Airport before he returned to South Korea.
Bosworth was due to brief South Korean Foreign Minister Yu Myung-Hwan and chief nuclear negotiator Wi Sung-Lac before holding a press conference at 0600 pm (0900 GMT).
The North quit the six-nation nuclear disarmament negotiations in April before staging its second atomic weapons test the following month.
Washington says Bosworth's mission was solely to assess whether the North is willing to return to the talks, and whether it will reaffirm its commitment to a 2005 accord designed to scrap its nuclear arms program.
Analysts, however, say Pyongyang appears to have a grander goal: a peace treaty with the United States to formally end the 1950-53 Korean War.